Long answer: Plenty of RAM but might be slow on browsing due to the older processor. It’s better to use Brave instead of Firefox because Brave is faster.
As @kommuni mentioned, a ThinkPad T480 with a 4-core CPU is a preferable choice. The ThinkPads with an s at the end of the model are intended to be more “portable” and less performant. A ThinkPad T460s is probably not worth your time (with Qubes or any other OS).
The specs are very similar to what I have in my current laptop. It’s usable, but it’s hard to be productive on it. Don’t spend too much on it, especially if the screen is less than 1080p.